The Sub-Balkan graben system of central Bulgaria

摘要: The Sub-Balkan graben system in central Bulgaria forms the present northern boundary of Aegean extensional region. This east-trending lies along southern flank Stara Planina range and consists mainly half-grabens. sedimentary fill grabens ranges age from late Miocene to Recent records initiation evolution system. is oldest becomes progressively younger west east, indicating a diachronous development grabens. Grabens are formed hangingwalls south-dipping low-angle normal faults which have been displaced by higher angle foot Planina. Hangingwall rocks complexly faulted rotated such that some has down-to-the-north. Sredna Gora south part hangingwall block bounded on forming Thracian Basin. uplift rotation due footwall unloading margin Most topography result processes linked region superposed convergent features earlier extend back Eocene time.